have 03 renault kangoo 1.4 diesel and the fins broke on the heater motor and jammed. i have bought used motor and fitted but only speeds 1 and 2 work so wired up 1 st motor and it also only works on speeds 1 and 2. used motor came with resistor, can i test resistors ? when fins broke on motor it jammed and their was a burning smell seemed to be motor as when took out motor really smelt but it obvsiouly still works. any ideas what to test replace ? vehicle has air con and that still works on speeds 1 and 2.